The invention relates to fasteners more particularly intended to equip a fastener having a clasp for a watch strap in accordance with the claims.
Fasteners having a folding, snap-on clasp with or without an articulated, folding arm are known. In exemplified manner, EP 509,938 describes a folding clasp comprising two folding arms articulated to the ends of a central cover or stretcher. Each arm has a concavity permitting a locking by compressing said concavity on a rod or pin of the central cover. This notching device must be accurately manufactured in order to function correctively. It has proved disadvantageous that the limited elasticity, one-piece arms and the concavities lose their flexibility under the effect of a repeated compression.
EP 115,740 discloses another tuning fork-system, folding, snap-on clasp, which as a more stable construction and has large friction surface in order to bring about the notching of the folding arms. Mention is made of the significant force necessary for opening or closing the watch strap. This constitutes another disadvantage, because the user can damage his nails on activating the groove.
A third disadvantage relates to the reliability and security of known fasteners having a folding, snap-on clasp. The locking forces are difficult to regulate and have a risk of the clasp opening in an untimely manner.